Most prior art cross-country bindings hold the prior art cross-country ski boots by grasping the boot's protruding front lip. The boot is very flexible across the front, and the skier begins skiing by lifting the heel of one boot as if starting to walk. This heel lift requires use of the lower leg muscles. This lifting flexes the boot, and the foot achieves an almost tip-toe position, referred to as a push-off or toe-off position. Then, with the boot and foot so flexed, the skier pushes or "kicks" rearwardly. This kick or push requires extensive use of the skier's gastrocnemius-soleus complex and hip extensors. The rearward kick drives the ski backwardly, and it digs into the snow. The rearward push or "kick" then becomes an opposite forward reaction, which is transferred to the opposite ski causing it to glide forward. The sequence is repeated using alternate boots for kicking and gliding, and the skier moves along.
Because of the flexible nature of the prior art cross-country boots, which nature is dictated by function as explained, the prior art boots have several substantial drawbacks. First, the skier's foot and leg work against gravity, and as a result, the skier must exert a great deal of energy in order to flex the boot and kick. In the course of a cross-country ski trip, this results in an exorbitant kilocalorie expenditure. Furthermore, this effort places a great deal of force or strain on a small area of the tendon in the rear of the leg, and this can cause tendon damage. Also, the associated foot, ankle and leg muscles are used and strained, and this often causes soreness, fatigue and sometimes even muscle damage.
Also, since the prior art cross-country boot must be flexible, it is generally made of soft leather or a plastic material, neither of which provides much warmth for the skier's foot and neither of which is waterproof.
Another major drawback of the prior art cross-country ski boot becomes evident when the skier attempts to turn or ski downhill. Turning is accomplished by transmitting pressure through the ski boot or against the sides of the boot to the edges of the skis. While this is easily done with the rigid downhill ski boots, it is difficult to do with the prior art cross-country ski boot, the soft sides of which tend to collapse or compress rather than transmit any force from the foot to the skis. Therefore, the skier does not have very good ski control when sliding downhill. Further, since the soft side of the prior art boots provide no lateral support, they make it necessary for the skier to use the inverters and everters of the ankles a stabilizers for the foot, thereby increasing muscle strain.